My lab had purchased a manual water bath viscometer. It uses the very small capillary glass. I test mainly petroleum and non-polar liquids with this. ASTM D445
As of now I am looking for a "safer" less toxic way to properly clean this glass wear, without compromising the calibration or surface of the glass. I wish not to use a very caustic mixture as over time this can effect the instrument up to 20%. Also there could possibly be small amounts of silicone in the samples that I also need to dissolve without damaging the glass wear.
Has anyone used solvents other than hexane, isopropanol , xylene and chromic acid? I have heard there are NOCHROMIX cleaners, is anyone familiar with the success rate of these?
I have tried, Mineral S. and acetone. I'm am uncertain of its effectiveness however.
Thank you!
To remove organic residues we use piranha solution instead of chromic acid. Piranha solution is a mixture of sulfuric acid and H2O2 which is strongly oxidizing. We mainly use it for quartz sample cells but it should also work for the capailaries of an Ubbelohde viscometer. An alternative could be the cuvette rinsing fluid from Hellma (Hellmanex) and afterwards extensive rinsing with deionised water.
─ Silicone grease on glass labware (possibly ground surfaces) can be cleaned with decalin (decahydronaphthalene) followed by acetone. Either diethyl ether or xylene can alternatively be used.
─ Xylene, as glass cleaner, can be often substituted by a less hazardous mixture of either petroleum ether, pentane, n-hexane, or ligroin; with isopropyl alcohol (approx. 5─6:1 v/v); or by the former solvent followed by isopropyl alcohol.
Dear all, if you have a new equipment than I think the best option is to respect the cleaning procedure furnished with the material. As you know these cappilaries are shear sensitive, any change in the surface roughness will change the viscometer constant. Most washing solutions such as piranha and HF are really agressive and may impart irreversible surface damage and change. My Regards
Abdelkader BOUAZIZ Then what would be your alliterative recommendation? That is my worry, is effecting the calibration due to how small and fragile these capillaries are. Thanks.
Dear all, my recommandation is to keep cleaning following the equipment procrdure. Generally, very diluted solutions are analyzed, so it is not really sticking so much to the glassware, which means it doesn't need such high need for cleaning. After use cleaning with the pure solvent used in the experience followed by water rincing which may be accompagned with sonication, this is the way I did my self. My Regards
Abdelkader BOUAZIZ I am using very concentrated solutions. I wish I were able to use less concentrated and get away with easy cleaning. I am evaluating additives the contractions are rather high. However, if I ever do diluted samples I will keep this in mind! Thank you!
Dear all, note that cappilary viscometers are not suitable and not accurate for highly concentrated solutions, my advice is to use other instruments such as cone and plate rheometer or the falling ball viscometer. Wish you good luck
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